common/LaaProduction/EquipmentsResult.cs

namespace LaaProduction
{
    using System.Collections.Generic;
    using System.Runtime.InteropServices;

    [ClassInterface(ClassInterfaceType.AutoDual)]
    public class EquipmentsResult
    {
        private readonly Queue<Equipment> equipments = new Queue<Equipment>();

        public Error Error { get; set; }

        public bool Succeeded => this.Error is null;

        public int Count => this.equipments.Count;

        public Equipment Next
        {
            get
            {
                var next = this.equipments.Dequeue();

                this.equipments.Enqueue(next);

                return next;
            }
        }

        internal void AddRange(IEnumerable<Equipment> equipments)
        {
            if (equipments is null)
            {
                return;
            }

            foreach (var e in equipments)
            {
                this.equipments.Enqueue(e);
            }
        }
    }
}